Beatriz Rasines

Carbosilane dendrimer nanotechnology outlines of the broad HIV blocker profile.

Researchers have been working hard for more than 20 years to develop safe and effective microbicides to empower women to better control their own sexual life and to protect themselves against HIV and other sexually transmitted infections (STIs). Microbicide classes include moderately specific macromolecular anionic polymers that block HIV and other STIs, and HIV specific drugs that inhibit viral entry and reverse transcription. Based on innovative nanotechnology design, we showed a novel water-soluble anionic carbosilane dendrimer (2G-S16) as a propitious molecule against HIV-infection. A state-of-the-art research was accomplished that focused on biomedical cutting-edge techniques such as in vitro and in vivo cytotoxicity assays performed on female rabbit genital tracts, simulate in vitro model of vaginal epithelium in order to evaluate HIV transmission blockade through the monolayer, complete gene expression profiling experiment to study deregulated genes after 2G-S16 exposition, molecular dynamics simulation of 2G-S16 molecule against principal proteins of HIV particles and pro- and anti-inflammatory cytokine profile study. Therefore, a high-throughput study and detailed analysis of the results were achieved in this article. We provided promising outcomes to encourage 2G-S16 as a hopeful microbicide.

In Vitro Studies of Water-Stable Cationic Carbosilane Dendrimers As Delivery Vehicles for Gene Therapy Against HIV and Hepatocarcinoma

Here we present a synthetic procedure for water-stable carbosilane dendrimers containing ammonium groups at the periphery of type Gn-{[Si(CH2)3N+(Me)(Et)CH2CH2N+Me3]x (CF3SO3 -)y} which have been used as non-viral vectors for transfecting different types of nucleic acids against two different medical problems, HIV and hepatocarcinoma. These systems have shown to be non-toxic in both PBMC and HepG2 cell lines under the experimental conditions and are able to form nanoconjugates with nucleic acids perfectly stable over time and in a wide range of pH values, which leads to the conclusion that the interaction between dendrimer and nucleic acid is very strong. In addition, a high degree of transfection using these nanoconjugates has been observed, ranging from 70-90% depending on the generation and in the particular case of PBMC transfection with anti-HIV oligonucleotides. However, besides of the good properties shown by the dendrimers here prepared as transfecting agents, only moderate effect was observed in functional experiments for hepatocarcinoma, as a result of the strong interaction between dendrimer and nucleic acid. Nevertheless, it is important to mention that an IRS-4 knock-down of 40% in HepG2 achieves an analogous degree of cell sensitization to cancer treatment, which may represent a major advance in the hepatocarcinoma treatment when appropriate dendrimers as transfection agents are used.

In vitro evaluation of the effectiveness of new water-stable cationic carbosilane dendrimers against Acanthamoeba castellanii UAH-T17c3 trophozoites.

Acanthamoeba is one of the most common free-living amoebas which is widespread in the environment and can infect humans, causing diseases such as keratitis and encephalitis. In this paper we examine for the first time the amebicidal activity of the family of cationic dendrimers nG-[Si{(CH2)3N+(Me)(Et)(CH2)2NMe3+}2I−]x (where n denotes the generations: zero (n = 0, x = 1), first (n = 1, x = 4), and second (n = 2, x = 8); for simplicity, they were named as 0G-CNN2, 1G-CNN8, and 2G-CNN16, respectively) against Acanthamoeba castellanii UAH-T17c3 trophozoites. In order to test the amebicidal activity, we cultured the strain A. castellanii UAH-T17c3 in PYG-Bactocasitone medium and later, we treated it with different concentrations of these dendrimers and monitored the effects and damage by optical count, flow cytometry, and scanning electron microscopy. The results showed that all the nanosystems assayed had a strong amebicidal activity. The dendrimer 1G-CNN8 was the most effective against the amoeba. In the morphology of treated throphozoites of A. castellanii UAH-T17c3 analyzed by light and scanning electron microscopy techniques, morphological changes were evident in amoeba cells, such as loss of pseudopodia, ectoplasm increase, roundness, and cellular lysis. Furthermore, flow cytometry results showed alterations in cell granularity, which was dose–time dependent. In conclusion, this family of cationic carbosilane dendrimers has a strong amebicidal activity against the trophozoites of A. castellanii UAH-T17c3 in vitro. They could potentially become new agents significant to the development of new amebicidal compounds for prevention and therapy of Acanthamoeba infections.

Synthesis and fluorescent properties of cationic carbosilane dendrimers containing eugenol linkers for their use in biomedical applications

A synthetic strategy has been carried out to prepare a new family of dendrimers containing eugenol linkers between the carbosilane scaffold and the peripheral amine or ammonium groups, of type Gn-[Si(CH2)3C6H3(OMe){O(CH2)2NMe2}]m or Gn-[Si(CH2)3C6H3(OMe){O(CH2)2NMe3+I−}]m respectively. Cationic carbosilane dendrimers have shown fluorescent properties due to the presence of the aromatic rings. A preliminary study of the interaction of dendrimers with two model drugs as examples of Active Pharmaceutical Ingredients (APIs) has been performed by fluorescence and NMR methods. This study determines the ability of these dendrimers to interact with potassium phenoxymethylpenicillin (Penicillin VK) as an example of an anionic low molecular weight drug entity or bovine serum albumin (BSA) as a biopharmaceutical drug protein entity, affording an appropriate dendritic system for its use in certain biological applications like drug delivery.

Characterization of carboxylate-terminated carbosilane dendrimers and their evaluation as nanoadditives in capillary electrophoresis for vegetable protein profiling.

Protein profiles are becoming an important tool to differentiate and classify varieties of several cultivars and to obtain a specific fingerprint for them. The use of protein profiles for these purposes needs to achieve high separation efficiencies to obtain a high number of well resolved peaks. In this work, carbosilane dendrimers with interior carbon-silicon bonds and negatively charged in the dendrimer surface with carboxylic acid as functional groups were employed as nanoadditives to separate soybean and olive seeds proteins. First, these dendrimers were characterized using CE to evaluate their possible impurities. A potentiometric titration was later carried out to determine their pK(a) values. Afterwards, the characterized dendrimers were used to improve the protein profiles obtained by EKC for vegetable proteins. Different dendrimer generations (G1, G2, and G3) and concentrations (0.01-1% m/v) were tested. The highest dendrimer generation G3 at 0.1% (m/v) allowed observing the best protein profiles for soybean and olive seeds. These results demonstrate that carboxylate-terminated carbosilane dendrimers are attractive nanoadditives in EKC for the effective separation of vegetable proteins.

CHAPTER 7:Dendrimers

Dendrimers are polymeric macromolecules constituted of a repetitive sequence of monomers growing step-by-step from a multifunctional core in a radial iterative fashion, not by polymeric reactions. Their synthesis offers the opportunity to generate monodisperse, structure-controlled architectures resulting in utility in specific biomedical applications. Advances in the role of molecular weight and architecture on the behaviour of these dendrimers, together with recent progress in the design of biodegradable chemistries, has permitted the application of these branched polymers as antiviral drugs and in other applications outside medicine.